索马里越赤道气流对越南降水变化的影响

Impacts of Somali Cross-Equatorial Flow on Precipitation in Vietnam

基于1979—2002年CMAP全球降水资料和NCEP/NCAR再分析资料,研究了越南降水的季节和年际变化特征及其受索马里越赤道气流的影响。结果表明,越南南北方降水具有不同的季节和年际变化特征,南方降水主要集中在夏季和秋季,且夏、秋季降水的变化呈反位相关系,而北方降水则集中在夏季。夏季索马里气流与同期及后期越南南方降水有很好的相关性,同期为显著的正相关,后期为显著的负相关。相对而言,索马里越赤道气流和越南北方降水的关系不显著。另外,夏季赤道印度洋西风与越南夏秋季降水的相关与索马里气流类似,表明索马里越赤道气流可能是通过改变纬向水汽输送来影响越南南方降水。

Based on the CMAP global precipitation data and NCEP/NCAR reanalysis data from 1979 to 2002, the characteristics of seasonal and interannual variability of Vietnam precipitation is analyzed, and the influence of Somali cross-equatorial flow on Vietnam precipitation is also studied. Resuits show that southern precipitation has seasonal and interannual variability characteristics different from those of northern precipitation. Southern precipitation mostly happens in summer and autumn, and the two season rainfalls show an antiphase relation;while northern precipitation mainly concentrates in summer. The strength of Somali flow in summer has a good correlation with southern precipitation in summer and autumn, the former is a significantly positive correlation, and the latter is a remarkable negative correlation;however, the relationship between Somali flow and northern precipitation is not evident. Research also indicates that the correlation between the west wind over the equatorial Indian Ocean in summer and southern Vietnam precipitation is similar to Somali flow, therefore it can be inferred that through on in southern Vietnam. modifying meridional water-vapor transfer, Somali flow affects precipitation in southern Vietnam.